Elastomeric articles produced from thermoplastic elastomers such as block copolymers are well known. Thermoplastic elastomers, such as copolymers having blocks of monovinylidene aromatic monomer and conjugated diene monomer are often blended with other thermoplastic polymers, for example, polypropylene, polystyrene, polyethylene, or ethylene vinyl acetate copolymers, to improve processing. These thermoplastic polymers tend to reduce the viscosity of the elastomers and provide improved processability by reducing the elastic nature of the composition, as described in U.S. Pat. Nos. 4,329,309; 4,173,612; 4,305,990; 4,977,014; and 6,410,129 B2, the teachings of which are incorporated herein by reference.
Typically, the elastomeric block copolymer is compounded with a thermoplastic polymer and fed to an extruder to produce film, fiber or netting materials. However, this process is expensive due to the amount of scrap material generated, and the potential of low quality or non-homogeneity of the product. Further, it is also known in the art that blends of elastomeric block copolymer and thermoplastic polymers can be directly fed to converting extruders to produce useful articles. However, this process requires feeding systems to accommodate multiple components, and the potential for low quality or non-homogeneity of the converted article remains. An additional disadvantage of the compositions discussed above includes the production of “opaque” or “hazy” products (that is, low transparency) due to significant differences in the refractive indices of the polymers.
Therefore, what is needed is a “transparent” block copolymer or blend composition that can be converted into a useful “transparent” elastomeric article. Further, what is needed is a blended product of an elastomeric block copolymer and a thermoplastic block copolymer that can be produced in the same polymerization process, blended while in solution and produced as a single pellet product, eliminating the need for compounding or direct feed of multiple components to an extruder.